Tracking assets using Global Positioning System (GPS) technology is becoming widely used. However, for most users, latitudinal and longitudinal coordinates are generally not a very useful form of location information. Instead, it is more useful for users to have the coordinates provided in reference to one or more features or landmarks that are commonly known.
In most regions of the world, there exists so-called “geo-reference data” that provides the coordinates of well known features and landmarks, such as roads, rail lines, topology, land use and place descriptions. By combining the coordinates of a tracked asset with information about nearby geo-reference features and landmarks a useful description of the asset location can be created. For example, by incorporating the relevant geo-reference data, location information may be given in the following forms: “12.6 miles southeast of Gary, Ind.; 112 meters out of 629 Rockledge Drive, Rockledge, Fla.,” or “¼ mile from the peak of Mount Everest.”
Such location information may be provided graphically on electronic maps, in text or in other data format. These kinds of descriptions are readily understood as long as the selection of geo-reference features and presentation methods are appropriate for users.
Several approaches have been adopted for representing geo-reference features and landmarks. One approach is to represent landmarks such as cities as a point. Alternatively, it is also common to describe landmarks in more detail as a defined area. In the simplest form, a landmark area can be defined as a center point with a radius. Such a description provides a user with more detail information, such as whether an asset is located at the landmark. That is, whether the coordinates of the asset are within the defined area of the landmark. For example, one can determine whether a trailer asset is in a trailer yard by first describing the yard as a center point with a radius. Then the asset is checked to see if it is within the radius. If the asset is within the radius then the asset is located at the landmark.